pv capacity methodologies
DESCRIPTION
December 2007 Conference Call Richard Perez, SUNY PV Capacity MethodologiesTRANSCRIPT
Moving Toward Consensus on a Photovoltaic Generation Capacity Valuation Methodology
Richard Perez State University of New York at AlbanyMike Taylor Solar Electric Power AssociationTom Hoff Clean Power ResearchJP Ross Vote Solar
OBJECTIVE
The U.S. Department of Energy’s Solar America Initiative has provided funding to evaluate the variety of photovoltaic capacity valuation methods and to bring the solar industry, electric utility, and research communities together with the goal of consensus on the most appropriate PV generation capacity valuation methodology.
LOAD
PV
At Issue: Quantifying PV Capacity Credit
Perez, Taylor, Hoff & Ross
LOAD
PV
At Issue: Quantifying PV Capacity Credit
Perez, Taylor, Hoff & Ross
There are three operational definitions that need to be distinguished that are an important part of the present discussion.
1. A method is a specific mathematical model (formula) for calculating a PV capacity value.
2. Each method may have different input variables, such as electric system demand, PV capacity and performance, time parameters, number of installations, geography, and/or back-up/storage.
3. The sampling interval of the input variables can be adjusted according to utility, regulatory, or other preferences
There are three operational definitions that need to be distinguished that are an important part of the present discussion.
1. A method is a specific mathematical model (formula) for calculating a PV capacity value.
2. Each method may have different input variables, such as electric system demand, PV capacity and performance, time parameters, number of installations, geography, and/or back-up/storage.
3. The sampling interval of the input variables can be adjusted according to utility, regulatory, or other preferences
We assembled a catalogue of 8 methodologies
ELCC Effective load carrying CapabilityLDMC Load Duration Magnitude CapacityLDTC Load Duration Time CapacitySLC Solar Load Control CapacityMBESC Minimum Buffer Energy Storage capacityTSW Time-Season-WindowCF Capacity FactorDTIM Day-Time Interval matching
LOAD
Perez, Taylor, Hoff & Ross
X MW PV
LOAD NEW LOAD
Perez, Taylor, Hoff & Ross
Load increase, constant LOLP
X MW PV
LOAD NEW LOAD
Perez, Taylor, Hoff & Ross
Y MW = ELCC
Load increase, constant LOLP
X MW PV
%ELCC = Y / X
LOAD NEW LOAD
Perez, Taylor, Hoff & Ross
1,000
1,100
1,200
1,300
1,400
1,500
1,600
Top of the load duration curve
load
(MW
)
load duration without PV
load duration with PV at 20% penetration
Load duration with ELCC capacity installed
Perez, Taylor, Hoff & Ross
40%
50%
60%
70%
80%
90%
100%
p
8760 hours
LDMC = average relative PV output for these points
LDMC = average relative PV output for these points
LDMC
Perez, Taylor, Hoff & Ross
40%
50%
60%
70%
80%
90%
100%
p
8760 hours
LDMC = average relative PV output for these points
LDMC = average relative PV output for these points
40%
50%
60%
70%
80%
90%
100%
0% 20% 40% 60% 80%
p’
LDTC = average relative PV output for these points
LDTC = average relative PV output for these points
LDMC
LDTC
Perez, Taylor, Hoff & Ross
Perez, Taylor, Hoff & Ross
1000
1100
1200
1300
1400
1500
1600
500 sorted highest loads
load
(MW
)
X = Installed PV
L
Load duration curve
Load duration curve with PV
Upper section of load duration curve
Solar-Load-Control-based Capacity
SLC
Perez, Taylor, Hoff & Ross
1000
1100
1200
1300
1400
1500
1600
500 sorted highest loads
load
(MW
)
X = Installed PV
L
Load duration curve
Load duration curve with PV
SLC: demand response needed to achieve peak demand reduction = X
Upper section of load duration curve
Solar-Load-Control-based Capacity
SLC%SLC = (X-Y) / X
Perez, Taylor, Hoff & Ross
1000
1100
1200
1300
1400
1500
1600
500 sorted highest loads
load
(MW
)
X = Installed PV
LY
Load duration curve
Load duration curve with PV
SLC: demand response needed to achieve peak demand reduction = X
Same amount of demand response, but applied without PV
Upper section of load duration curve
Solar-Load-Control-based Capacity
SLC
Perez, Taylor, Hoff & Ross
1000
1100
1200
1300
1400
1500
1600
500 sorted highest loads
load
(MW
)
X = Installed PV
LY
Load duration curve
Load duration curve with PV
SLC: demand response needed to achieve peak demand reduction = X
Same amount of demand response, but applied without PV
Upper section of load duration curve
Effective capacity = X - Y
Solar-Load-Control-based Capacity
SLC%SLC = (X-Y) / X
Perez, Taylor, Hoff & Ross
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500
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Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
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2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
MBESC
Perez, Taylor, Hoff & Ross
Installed PV capacity
x
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
MBESC
Perez, Taylor, Hoff & Ross
Installed PV capacity
x
Minimum Buffer Energy Storage (MBES)
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
MBESC
Perez, Taylor, Hoff & Ross
Installed PV capacity
x
Minimum Buffer Energy Storage (MBES)
Same storage applied without PV
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
MBESC
Perez, Taylor, Hoff & Ross
Installed PV capacity
x
Minimum Buffer Energy Storage (MBES)
Same storage applied without PV
Achieved peak reduction with MBES, but w/o PV
Y’
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
Achieved peak reduction with MBES, but w/o PV
Installed PV capacity
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
0
500
1000
1500
2000
2500
3000
Time of Day
Load
(MW
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000Load - PV
LOAD
Peak reductionthresholdPV output
NominalPV output W/kW-ptc
oo
x Y’
Minimum Buffer Energy Storage (MBES)
Same storage applied without PVEffective capacity = X – Y’
MBESC
%MBESC = (X-Y’) / X
Perez, Taylor, Hoff & Ross
TSW
Perez, Taylor, Hoff & Ross
TSW
Perez, Taylor, Hoff & Ross
TSW
Perez, Taylor, Hoff & Ross
TSW
Perez, Taylor, Hoff & Ross
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 11 21 31 41 51
% rated PV output
HORIZONTAL PV
0% 20% 40% 60% 80% 100%
Probability
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 11 21 31 41 51
% rated PV output
HORIZONTAL PV
0% 20% 40% 60% 80% 100%
Probability
Capacity credit
TSW
Perez, Taylor, Hoff & Ross
Average OutputInstalled Capacity%CF =
Perez, Taylor, Hoff & Ross
DTIM
Sampling interval a few secondsDispatch cycle several sampling intervalsEvaluation period day/time window
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
7:30 8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30
Ten Second Period Ending
Cha
nge
in %
of F
ull O
utpu
t
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Tota
l Gen
erat
ion
in M
W
PV Power generation
10 seconds variability
Maximum PV outputMaxSolarPowerDC defines best solar output capacity
Minimum PV outputMinSolarPowerDC defines least solar output capacity
Three time references
Perez, Taylor, Hoff & Ross Source: T. HANSEN
Top of the load duration curve
LOA
D
load duration without PVload duration with PV
X = installed PV Capacity≈ MaxSolarPowerDC
Load Duration Curves with Time Resolution Equal to Dispatch Sampling Interval
DTIM
Perez, Taylor, Hoff & RossPerez, Taylor, Hoff & Ross Source: T. HANSEN
Top of the load duration curve
LOA
D
load duration without PVload duration with PV
Top of LD curve w/o PV
Top of LD curve with PV
X = installed PV Capacity≈ MaxSolarPowerDC
Z = difference between tops of LD curves ≈ MinSolarPowerDC
Capacity Credit
%DTIM = Z/X
Load Duration Curves with Time Resolution Equal to Dispatch Sampling Interval
DTIM
Perez, Taylor, Hoff & RossPerez, Taylor, Hoff & Ross Source: T. HANSEN
Rochester Gas & Electric
Nevada Power
Portland General
• 3 utilities
• Hourly Load and PV generation data for 2003
• PV capacity penetration from 1% to 20%
Perez, Taylor, Hoff & Ross
NEVADA POWER
Perez, Taylor, Hoff & Ross
0%
20%
40%
60%
80%
100%
0% 5% 10% 15% 20%
Grid penetration
Effe
ctiv
e C
apac
ityELCC LDMCLDTC SLCMBESC TSWpeakTSWtime CFDTIM
PORTLAND GENERAL
Perez, Taylor, Hoff & Ross
0%
20%
40%
60%
80%
100%
0% 5% 10% 15% 20%
Grid penetration
Effe
ctiv
e C
apac
ityELCCLDMCLDTCSLCMBESCTSWpeakTSWtimeCFDTIM
0%
20%
40%
60%
80%
100%
0% 5% 10% 15% 20%
Grid penetration
Effe
ctiv
e C
apac
ityELCC LDMCLDTC SLCMBESC TSWpeakTSWtime CFDTIM
ROCHESTER GAS & ELECTRIC
Perez, Taylor, Hoff & Ross
0%
20%
40%
60%
80%
100%
0% 5% 10% 15% 20%
Grid penetration
Effe
ctiv
e C
apac
ityELCC LDMCLDTC SLCMBESC TSWpeakTSWtime CFDTIM
ROCHESTER GAS & ELECTRIC
General agreement between most metrics based upon a physical definition of capacity
Perez, Taylor, Hoff & Ross
Springerville
Demand-Time Interval Matching (DTIM)
4.6 MW Springerville PV Plant Actual Production Data
Tucson Electric Power
Perez, Taylor, Hoff & Ross
Springerville
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
7:30 8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30
Ten Second Period Ending
Cha
nge
in %
of F
ull O
utpu
t
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Tota
l Gen
erat
ion
in M
W
Demand-Time Interval Matching (DTIM)
4.6 MW Springerville PV Plant Actual Production Data
Tucson Electric Power
Perez, Taylor, Hoff & Ross
Springerville
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
7:30 8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30
Ten Second Period Ending
Cha
nge
in %
of F
ull O
utpu
t
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Tota
l Gen
erat
ion
in M
W
Demand-Time Interval Matching (DTIM)
4.6 MW Springerville PV Plant Actual Production Data
Tucson Electric Power
Perez, Taylor, Hoff & Ross
Springerville
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
7:30 8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30
Ten Second Period Ending
Cha
nge
in %
of F
ull O
utpu
t
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Tota
l Gen
erat
ion
in M
W
Demand-Time Interval Matching (DTIM)
4.6 MW Springerville PV Plant Actual Production Data
Tucson Electric Power
Capacity credit
Perez, Taylor, Hoff & Ross
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
40 participants almost 50% from utilities
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
40 participants almost 50% from utilities
FOCUS ON METHODOLOGY
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
Is deterministic (rather than statistical)
Provides operational measure of firm capacity when back-up/storage is available
Can be used to perform worst case analysis and addresses short term variability issues
Based on load duration curve
Accounts for effect over all hours
Accounts for PV penetration
Based on actual PV output/load correlation
SUBSTANCEHas been implemented by utilities
*Produces results that are consistent with other metrics that account for PV penetration
Based on concepts familiar to utilities
Simple to describe
Simple to implement
PROCESS
DTIM
CFTSW (peak/time)
SLCMBESCLDTC LDMCELCCImportance
MethodsAttributes
WORKSHOP QUESTIONS
Methods
• Are there clarifying questions about the methods presented?• Are there methods that should be included but are missing?• Are there attributes that should be included but are missing?• What level of important should be assigned to the various attributes?
Narrowing the Methods
• What methods have clear weaknesses and should not be considered?• What are the strengths or weaknesses of the remaining methods, recognizing the diversity of load profiles, reliability criteria and other generation resource differences across utilities?• Are there methods that have clear advantages?• Is there one method that can be most practically utilized by utilities to calculate PV capacity accurately and appropriately?
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
40 participants almost 50% from utilities
FOCUS ON METHODOLOGYGeographyTime scale
WORKSHOP QUESTIONS
Geographical Dispersion and Sample Intervals
• Under what conditions should different time sampling intervals (10 second, 1 hour, etc) be utilized? What time sampling intervals are used within other utility operations?• Under what conditions should or shouldn’t multiple installations over distances be utilized?• How do different time and geography sampling intervals address different concerns? (short time over wide geography, or vice versa)• How important is a back-up/storage input variable as a component of a capacity method?
Methods in Practice• How can the best method or methods be implemented in actual practice within the utility environment?• As individual utility control areas experience high PV penetration, should• reliability criteria be evaluated over multiple control areas?
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
40 participants almost 50% from utilities
FOCUS ON METHODOLOGYGeographyTime scale
Input data and logistics
WORKSHOP QUESTIONS
Data Logistics
• If the appropriate time-interval is available, is satellite modeled data acceptable? Under what conditions?• If appropriate satellite data is unavailable, are reference site proxies acceptable? Under what conditions?• What contingency plans could be utilized for new installations with no operational history?• For what sizes or types of systems is high-quality on-site monitoring necessary to collect short time-intervals versus proxy data from reference locations?
Stakeholders WorkshopSolarPower 2007, Long Beach, CA, 9/27/07
40 participants almost 50% from utilities
FOCUS ON METHODOLOGYGeographyTime scale
Input data and logisticsValue of capacity (who pays for it and how)Cost of PVOwnership of PVVery high penetration of PVPV alone, vs. synergy with storage and controlsRigorous LOLP simulation
FOCUS ON METHODOLOGY
STRAW POLL• Load duration methods• ELCC• MBES-SLC• DTIM• Time-Season-windows• Capacity Factor
0
5
10
15
20
25
LDMETHODS
ELCC SLC /MBES
DTIM TSW CF
IndustryGovernmentUtilitiesALL
GeographyTime scale
Continued discussion with stakeholdersvia workshops and publications
0
5
10
15
20
25
LDMETHODS
ELCC SLC /MBES
DTIM TSW CF
IndustryGovernmentUtilitiesALL